The very considerable development of digital telecommunication systems, using cable, satellite or the airwaves, is causing a constant and sustained rise in the demand for interactive applications broadcast by these digital telecommunication systems, interactive applications which are or are not associated with television programs.
These applications may involve services as diverse as weather forecasts, management of stock market portfolios, TV, radio or similar magazine-type applications.
In general, and in order to allow lasting growth of the development of these applications, on account of the increasing complexity of these applications and of the services provided by them, the terminals for accessing these applications, which initially consisted primarily of TV receivers furnished with a remote control module, have evolved toward computer terminals furnished with capabilities for processing video images and for sound restoration, which apparatuses are more prosaically referred to as “lounge computers” within the mass-market arena.
On account of this evolution, the terminals for accessing these applications being thus endowed with evermore powerful operating systems, there is a great demand for access to evermore sophisticated applications.
On account of the very diverse, even disparate nature of the terminals for accessing these interactive applications, it being possible for applications of this type to be accessible by way of very different systems such as OPEN TV marketed by the OPEN TV Incorporated company in the United States, Media Highway, distributed in France by the company CANAL+, Mheg open system complying with the ISO standardization system, and JAVA system dedicated to television, currently being set up, the development of interactive applications is very complex, insofar as such development can be envisaged only as a function of the access system implemented.
Stated otherwise, with a view to such development, the latter can be undertaken only in respect of a given operating system corresponding to that of the final access system used.
Under such conditions, the aforesaid interactive applications are confronted, for each operating system considered, with the following constraints:                definition of the structure of the interactive application considered and of its logic model, an interactive application being composed of scenes, each scene being itself composed of virtual objects formed by diverse objects or components while allowing representation;        definition of the characteristics of the access terminal, or target platform allowing access to or the execution of this interactive application, these characteristics possibly comprising, in particular, the RAM random access memory size available, the accessible fonts and the available color palettes;        discrimination between permanent elements or objects, downloaded with the application, and necessary for the minimum functioning of the application, temporal elements, required at a given instant, broadcast cyclically;        updating of an interactive application or of one or more scenes on the basis of data internal or external to the access system;        reuse of objects, virtual objects of a scene or of one or more scenes themselves;        association with the events external to the access system, which are entered via a keyboard, a numerical pad or a television remote control package, a modem or a microprocessor card, and with the events internal to the access system, such as timeouts, a control language sufficient to endow the application with its interactive nature;        monitoring of the construction of a scene, of its representation and of the stringing together of successive scenes.        
Whereas the aforesaid interactive applications are currently constructed for the and dedicated to the operating system of the platform or of the access system, these applications must, at present, be constructed within the corresponding strict framework.